\documentclass{slides}
%%% BEGIN PREAMBLE

\usepackage{geometry}
\geometry{screen}

\title{the slides}
\author{xing wenju}
\date{} % delete this line to display the current date

%%% BEGIN DOCUMENT
\begin{document}

\maketitle

here is what I do


\rowcolors[]{1}{blue!20}{blue!10} 
\begin{tabular}{l!{\vrule}cccc} 
Class & A & B & C & D \\\hline 
X & 1 & 2 & 3 & 4 \pause \\ 
Y & 3 & 4 & 5 & 6 \pause \\ 
Z & 5 & 6 & 7 & 8 
\end{tabular}

\end{document}